The present technology relates to an audio-signal processing device, an audio-signal processing method, a program, and a recording medium. In particular, the present technology relates to an audio-signal processing device, an audio-signal processing method, a program, and a recording medium that can be applied to a headphone device, a speaker device, and so on that reproduce 2-channel stereo audio signals.
When audio signals are supplied to speakers and are reproduced, the sound image is localized in front of a listener. In contrast, when the same audio signals are supplied to a headphone device and are reproduced, the sound image is localized within the head of the listener to thereby create a significantly unnatural sound field. In order to correct the unnatural sound field in the sound-field localization by the headphone device, for example, Japanese Unexamined Patent Application Publication No. 2006-14218 discloses a headphone device adapted to achieve natural out-of-head sound-image localization as if audio signals were reproduced from actual speakers. In the headphone device, impulse responses from an arbitrary speaker position to both ears of a listener are measured or calculated and digital filters or the like are used to convolve the impulse responses with audio signals and the resulting audio signals are reproduced.
Now, a description will be given of an impulse response for sound-image localization for a headphone device. As illustrated in FIG. 28, it is assumed that a sound source SP whose sound image is to he localized is located directly in front of a listener M. Sound output from the sound source SP reaches the left and right ears of the listener M along paths having transfer functions HL and HR. Transform of such transfer functions HL and HR into representations along a time axis provides impulse responses for the left channel and the right channel.